An experimental study was made on a boundary layer diffusion flame over a flat plate. To know the effect of the diffusion flame on the boundary layer upstream flow, flow visualization by instantaneous and high speed schlieren photograph method was made, and measurements of mean velocity and turbulent intensity distribution by using a laser Doppler velocimeter, of temperature by R-type thermocouple and of concentration by gas chromatograph were made. Density and kinematic viscosity profiles were obtained by using data of concentration and temperature profiles.
The obtained results are follows :
1) It was shown that turbulent small eddies are vanished as flame exists, but large eddies are affected only a little.
2) In the flowfield of U=6.50 m/s V=1.29 cm/s, it was shown that the flame is blowing off at the downstream of x=40 mm. This may be due to turbulence generation, quenching of the wall and mainly flammability limit.
3) It was shown that local laminarization and downstream turbulence generation are mainly due to the fluid temperature.
4) It was shown that the existence of hydrogen gas at the front of the plate is caused by molecular diffusion of the hydrogen gas and/or recirculating flow.
5) It was shown that diffusion flame restrains mixing between free stream and fluid below the flame sheet.
6) In this study, the velocity overshoot at the flame sheet do not appear. This may be due to the lack of the fuel.
7) There comes velocity overshoot at the edge of boundary layer by virtue of the effect of combustion chamber in the flow field.
